Cross-border transactions usually trigger tax consequences in two or more states. In this ease not only the domestic
tax Law provisions of the states concerned apply, but also the provisions of the tax treaty the states have concluded.
The tax treaty provisions covering those cross-border cases aim at avoiding double taxation. They restrict the
domestic taxing power of the treaty states and in this way reduce the domestic tax liability. From a timing
perspective, this treaty protection is effective from the beginning to the end of the conditions provided for in the
treaty provisions for the avoidance of double taxation. In practice it is not yet clear according to which criteria the
facts triggering domestic tax liability are to be attributed to the treaty rules.
However, the answer to this question is vital for the protection of the taxpayer because it is decisive whether a fact
triggering domestic tax liability is already covered by the treaty protection or is not covered by the treaty norms any
longer. It is not only the aim of my research project to analyze single treaty issues but to cover all treaty provisions
with respect to their timing effects. Consequently, the project will try to form a basis for future decisions of
supreme courts. In addition, it will try to generate a higher degree of legal certainty in the application of tax treaty
Law.